Short answer. Generally yes. Rule 98, Section 5 requires a trustee to file a bond before entering on his duties, with failure to file treated as declining or resigning the trust, but the court may exempt a trustee the testator directed be exempt, or if all adult beneficiaries request it.
What the law says
Before entering on the duties of his trust, a trustee shall file with the clerk of the court having jurisdiction of the trust a bond in the amount fixed by the judge of said court, payable to the Government of the Philippines and sufficient and available for the protection of any party in interest, and a trustee who neglects to file such bond shall be considered to have declined or resigned the trust
Rule 98, Section 5 — Trustee must file bond. Read the full provision →
The bond as a precondition
The section requires that before entering on the duties of his trust, a trustee shall file with the clerk of the court having jurisdiction of the trust a bond in the amount fixed by the judge, payable to the Government and available for the protection of any interested party. The bond amount is not fixed by statute at a flat figure; the judge sets it for the specific trust, presumably scaled to the value and risk of the property being administered.
The consequence of not filing
Skipping the bond has a concrete legal effect: a trustee who neglects to file such bond shall be considered to have declined or resigned the trust — this is a real, automatic consequence, not a mere procedural lapse. A named trustee who simply never gets around to posting the bond is treated as having given up the position altogether, opening the way for the court to appoint someone else.
Two paths to exemption
The court may exempt a trustee under a will when the testator has directed or requested such exemption, and may likewise exempt any trustee when all persons beneficially interested in the trust, being of full age, request it. So a grandmother's will that expressly excuses her chosen trustee from bonding, or the unanimous agreement of adult beneficiaries, are the two routes by which the ordinary bonding requirement can be set aside.
The exemption is not permanent
Such exemption may be cancelled by the court at any time, with the trustee then required to forthwith file a bond — the protection a bond provides can be reinstated if circumstances later change. A change in the trust's circumstances, or a beneficiary later having second thoughts, can prompt the court to revisit an exemption that was granted earlier in the administration of the trust.